Dry cleaning



Aug. 20, 1963 M. B. MATHEWS 3,101,240

DRY CLEANING Filed June 29, 1953 3 Sheets-Sheet 1 g ze 83 3:1 7]

35- I 67 w I J6 Aug. 20, 1963 M. B. MATHEWS DRY CLEANING 3 Sheets-Sheet2 Filed June 29, 1953 INVENTORS Aug. 20, 1963 DRY CLEANING- 3Sheets-Sheet 3 Filed June 29, 1953 United States Patent 6 3,101,240 DRYCLEANING Martin B. Mathews, 5718 Drexel Blvd, Chicago, Ill.

Filed June 29, 1953, Ser. No. 364,844

s Claims. c1. s-mz My invention relates to the art of dry cleaning offabrics. It is particularly concerned with methods to insure maintenanceof high cleaning efficiency of the dry cleaning solvent in a simple andeffective manner.

In the usual process of dry cleaning fabrics, the soiled fabrics aresubjected to the action of a volatile organic solvent which isimmiscible with water as, for example, naphtha, Stoddard solvent, carbontetrachloride, gasoline, benzene, trichlorethylene, and the like. Suchsolvents are effective for the removal of grease or oil stains as wellas 3,101,240 Patented Aug. 20, 1963 cleaning operation of thatparticular batch of clothes. However, when a new batch of clothes orfabrics is introduced into the washer and is contacted with such drydust, dirt, lint and the like which commonly adhere to the grease andoil. It is conventional practice, in order to efiect the removal ofwater-soluble stains, such as those caused by various foods and thelike, to introduce into the volatile organic solvent in the washer asmall proportion of water, usually of the order of 0.05%. Thissulfoacetate; long chain alkyl sulfosuccinates such asdioctylsodiumsulfosuccinate; higher fatty acid monoglycerides such asmono-olein; higher fatty acid monoglyceride sulfates, such as mono-oleinmono-sulfates; and the like, the sulfates and sulfonates being used inthe form of salts. In the presence of such dispersing agents, the wateradded to the dry cleaning volatile organic solvent is very finely orcolloidally dispersed throughout the solvent so as to form what isapparently, to the naked eye, a homogeneous solution or what may becharacterized as a pseudo solution. While the advantages of the additionof water to a water-immiscible dry cleaning organic solvent and thesolubilizing of the water by means of an oil-soluble dispersing agenthave been, broadly speaking, heretofore konwn and used, the fullpotentialities of such existing knowledge have not been utilized inpractice because of the failure to understand certain aspects of thecriteria which govern the conditions under which the dry'cleaningoperation is best practiced. Thus, for instance, as almost invariablypracticed today, the amount of water added to the water-immiscible drycleaning solvent is based upon the weight and nature or condition of thefabrics added to the washer, a situation which is affected, among otherthings, by the relative humidity in the atmosphere and by other factors.The real key to the matter of insuring uniform superior dry cleaning inmodern reclamation systems lies in the discovery of the relationship andsignificance of electrical conductivity and the control and maintenanceof the conditions which account for certain minimum electricalconductivity essential for upon the'nature and condition of the fabrics.The remaining moisture in the dry cleaning organic solvent solutionremains more or less constant during the cleaning organic solventsolution, an additional amount of the waterdispersed therein isabstracted or absorbed by the clothes or fabrics. The result is that inthe dry cleaning operations conducted by any plant the moisture contentof the volatile organic solvent solution varies quite considerably'frombatch to batch of soiled fabrics and, at various stages of the usethereof for the cleaning of different batches of clothes or fabrics, themoisture content drops to a point where it is'inadequate to serve itsintended purposes, and the cleaning results are nonuniform..

In the dry cleaning step proper, as carried out in the so-called washeror wheel, it has been the practice to utilize various concentrations ofoil-soluble soaps or detergents as, for example, from a small fractionof one percent to as high as seven percent or even higher. During thecleaning of various batches of clothes, the concentration of the soap ordetergent decreases and it has, therefore, been the practice toreplenish the content from time to time. I

Despite all of such prior knowledge and practices, serious difiicultiesand lack of significant knowledge have existed so that, from a practicalstandpoint, it has not been possible for the operator of adry cleaningestablishment to carry out the dry' cleaning operations in such a manneras to obtain uniform substantially optimum results from batch to batchof fabrics being cleaned. I

It has been discovered that outstandingly satisfactory uniform cleaningresults of high efiiciency can be obtained in a simple, safe andpractical manner by procedure which [may readily be understood andpracticed lby the average operator of a dry cleaning establishment. Thisinvention is based, in part, on the discovery that, in dry cleaning withwater-immiscible organic solvent solutions containing an oil-solubledispersing agent or dry cleaning soap'or detergent and water, as. moreparticularly described below, the electrical conductivity of suchsolutions should be maintained at not less than about 1O l0f mhos toinsure uniformly superior overall re sults with respect to removal ofinert soil, water-soluble soil, prevention of soil redeposition,whiteness retention, avoidance of deleterious action on fabrics, economyof detergerrcy consumption, and freedom from interference with properoperation of the filtration and distillation systerns. The amount andtype of dry cleaning dispersing agent or detergent and the amount ofwater influence the degree of electrical conductivity imparted to thedry cleaning water-immiscible organic solvent. However, the state ofdistribution of the water is also a very important factor. In all cases,for the effective practice of this invention,

the water must be so finely or colloidally dispersed in the organicsolvent as to produce a substantiallyclear homogeneous solution,-so faras the naked eye is concerned, or what may be characterized as a pseudosolution. In this connection, it may be noted that it is entirelypossible to provide mixtures of water-immiscible organic solvents andoil-soluble dispersing agents and water, identical in proportions suchas have been found to be especially'efiective as hereafter described,and still be unsatisfactory for purposes of this invention because theirelectrical conductivity falls appreciably below the aforesaid value of10 10 rnhos due to the fact that the water is not properly distributedthrough the organic solvent. Hence, it will be understood that when Ispeak herein of solutions containing oil-soluble dispersing agents ordetergvgents and water, it will be understood that I mean such solutionswherein the water is so finely dispersed as to forma substantially clearhomogeneous solution in the water-immiscible organic solvent, as viewedby the naked soap or detergent during use of such solutions in thecleaning of a batch or successive batches of soiled fabrics, theelectrical com ductivity has dropped to appreciably below 1O- rnhos anamount of water and/or oil-soluble dispersing agent or dry cleaningdetergent is added to the solution so as to bring the electricalconductivity thereof to not less than the aforesaid minimum valuetheneof.

, This invention is particularly advantageously practiced with theutilization, as the oil-soluble dispersing, agent, of

sulfate and sul-fonate deter-gents containing an \alkyl group of atleast 8 carbon atoms and usually between 8 and 18 carbon atoms, in theform of salts thereof as, for instance, the alkali metal, ammonium andamine salts. In addition to the examples thereof described above, saltsof higher alkyl aryl sulfonates such as dodecyl benzene sul-fonate,octyl benzene sulfonate, nonyl naphthalene sulfonate, keryl benzene sulfonates, and the like can be utilized. It is also particularlyadvantageous, in the especially preferred embodiments of this invention,to utilize proportions of oilsoluble dispersing agent or detergent, onthe non volatile basis, of not less than about 1.5%, based on the volumeof the onganic solvent, and desirably within the range of about 1.5% toabout 3%, a good average being about 2%. In this connection, it will beunderstood that dry cleaning detergents are commonly marketed in theform of liquid or paste products and. frequently contain diluents,volatile ingredients and the like over and above the non-volatile drycleaning detergents proper. When I speak of, for example, 1.5% to 3% ofthe dry cleaning detergent, said percentages are in the non-volatileactive detengent basis.

The amount of water added to the water-immiscible dry cleaning solventshould, in the particularly preferred embodiments of this invention, notbe appreciably less than 0.2%, by volume, and most desirably ranges fromabout 0.2% to about 0.4%, it being relatively uncommon that this latterfigure will be exceeded. So far as actual cleaning practice goes, theseamounts of water are abnormally large but their use, under theconditions of the present invention, has been found to be mostadvantageous, cleaning of the fabrics being enhanced and subsequentspotting operations being reduced to a substantial The optimumconditions under which the dry cleaning operation should be conducted,taking into account the over-all aspects, therefore, will, in general,involve the utilization of la water-intnriscible dry cleaning organicsolvent solution containing from about 1.5 to about 3%, with a goodaverage of about 2%, of an oil-soluble sulfate or sulfonate detergentcontaining an alkyl group of at least 8 carbon atoms, and from about0.2% to about 0.4%, with a good average of about 0.3%, of water, theelectrical conductivity of said solution being not less than about 10x10mhos.

In the light of the foregoing description, it will be understood that,in the case of the foregoing dry cleaning organic solvent solutions, theelectrical conductivity varies more or less uniformly as a function ofthe water and detergent content of such solutions, the greater the waterand detergent content, at least within practical operating ranges, thegreater the electrical conductivity. Within any given system utilizing aparticular waterimmiscible dry cleaning organic solvent, a'particulardetergent and water, a substantially fixed relationship exists withrespect to the variability of the electrical conductivity as a functionof the quantity of detergent and water, particularly the latter,dissolved or colloidally dispersed in the organic solvent in the form ofthe aforesaid solutions. Thus, with any given system, for example, one

utilizing Stoddard solvent as the dry cleaning organic solvent,di-(Z-ethylhexyl) sodiumsulfosuccinate as the dispersing agent ordetergent, and distilled water as the source of 'water, it is possibleto plot curves showing the relationship of electrical conductivity todetergent and water content, particularly the latter, within practicallimits of the latter. Other curves can readily be prepared based uponelectrical conductivity data utilizing any specific system of materials.

:It will be understood that through continued use of the dry cleaningsolution on different batches of soiled fabrics, said solution builds upa constantly varying amount of soluble impurities which alfect to agreater or lesser extent, depending upon the amount and nature of suchimpurities, the electrical conductivity of said solution. In the usualcase, this is not sufficient susbtantiall'y to affect adversely theconductivity readings so far as their reflecting the condition of thesolution with respect to. the content of water and detergent therein. Inthe usual case, the electrical conductivity readings of a solutioncontaining a relatively high proportion of soluble impurities resultingfrom long continued use of the solution prior to distillation thereofwill show a somewhat lower conductivity than a similar pure organicsolvent solution containing only the same amounts of oil-solubledetergent and water. Suitable extrapolations can be resorted to, ifdesired, in situations of this kind, if deemed advisable, to take intoaccount the effect of soluble impurities on the electrical conductivityof repeatedly used dry cleaning solutions. Extreme temperaturevariations in the solution also influence the electrical conductivityvalue of the solution, high temperature increasing and low temperaturesdecreasing the electrical conductivity. Suitable allowances may be madefor such temperatures variations and optimum results are enjoyed bymaintaining the temperature of the solution between substantially 70 to85 F.

- ple, in dry cleaning systems which include a washer-filtertrapassembly reserved for the detergent solution, and a separate rinse andfilter system, and wherein said solution is continuously circulatedthrough said washerfilter-tnap assembly, the water-immiscible liquidorganic solvent is activated with the requisite amount of oil-solublenon-volatile dry cleaning dispersing agent or detergent and theresulting solution is circulated through said assembly to effect uniformdistribution of said dispersing agent or detergent throughout the entirebody of organic solvent in the assembly. The requisite amount of wateris then added and the resulting mixture is circulated through saidassembly whereby to solubilize the water throughout the system, so thatthe solubilized water solution passes through the filter, and forms asubstantially clear homogeneous solution having an electricalconductivity not less than about 1() '10' mhos. The solid fabrics to bedry cleaned are then subjected to the resulting dry cleaning solution inthe usual way, successive batches of soiled fabrics being dry cleaned.The electrical conductivity of the solution is measured and, if theelectrical conductivity has dropped to below the aforesaid value, anadditional amount of water and, if

necessary, detergent is added to bring the concentration dispersingagent or detergent to the organic solvent solutions will occur far moreinfrequently than the additions of water. In this connection, it will beappreciated that the solubility and stability of the oil-solubledispersing agent or detergent are such that the content hereofdiminishes quite slowly so that replenishing thereof isnecessary at onlyrelatively sporadic intervals. Hence, when the electrical conductivitydrops below abaut 1'0' -l0 mhos it will, in most cases, be necessary toadd only water in order to increase the electrical conductivity to avalue above said minimum figure. The content of oil-soluble detergent inthe dry cleaning solution can be determined from time to time .byheretofore known procedures. It may be found, in certain instances, thatwhen the electrical conductivity drops below the aforesaid minimum valuethere may be a deficiency of both detergent and water, and, in suchcases, both detergent and water will be added to bring the amountsthereof within thedesired or predetermined ranges as well as restoringthe electrical conductivity of the dry cleaning solution to a value notbelow said minimum figure. In the usual case, however, as stated, wateradditions alone will be sufiicient and the detergent content can bedetermined and maintained at desired proportions by procedures alreadyknown in the art.

An object of this invention is to provide an improved method formeasuring or determining the electrical conductivity of the solutioncirculating through the dry cleaning system for the purpose ofmaintaining high cleaning efliciency in a simple and efiective manner.In this respect all of the circulating solution in thedry cleaningsystem is circulated in a continuous manner through the conductivitymeasuring apparatus in order to obtain accurate and continuousmeasurements and determinations of the electrical conductivity thereof,and said conductivity measuring apparatus offers substantially noimpedance or restriction to the circulation of the solution.

A further object of this invention is to provide an improved method forautomatically supplying water to the solution in the dry cleaning systemfor automatically maintaining the electrical conductivity of thesolution at the desired values and to prevent an inadvertent andexcessive supply of water thereto. The water is introduced into thesystem for the purpose of maintaining a certain minimum electricalconductivity value necessary for efiicient cleaning, compatible withavoidance of damage to the fabrics, such as excessive wrinkling andshrinkage, which may be brought about by excess water. In this respectsuitable water pipes, water reservoir and solenoid valves and signallights controlled by the electrical conductivity measuring apparatusareutilized.

Other objects and advantages of this invention will become apparent tothose skilled in the art upon reference to the accompanyingspecification, claims and drawings in which:

. FIGURE 1 is an elevational view of a dry cleaning system useful incanrying out the method of this invention;

FIGURE 2 is a wiring diagram for the equipment illustrated in FIGURE 1;

FIGURE 3 is a vertical sectional view through the electricalconductivity responsive device and taken substantially along the line 33of FIGURES 2. and 4;

FIGURE 4 is a horizontal sectional view taken substantially along theline 44 of FIGURE 3;

FIGURE 5 is a horizontal sectional view taken substan tially along theline 55 of FIGURE 3;

FIGURE 6 is a sectional view of one of the spacer members illustrated inFIGURE 3;

FIGURE 7 is an enlarged partial sectional view showing the manner ofmaking electrical contact with the electrodes as illustrated FIGURE 3;

FIGURE 8 is a vertical sectional View similar to FIG- URE 3 butillustrating a further form of the invention and taken substantiallyalong the line 8-8 of FIGURE 9;

FIGURE 9 is a horizontal sectional view taken substantially along theline 99 of FIGURE 8;

FIGURE 10 is a horizontal sectional view taken substantially along theline 1010 of FIGURE 8;

FIGURE 11 is a sectional view through one of the spacer membersillustrated in FIGURE 8.

Referring first to FIGURE 1 there is generally illustrated aconventional dry cleaning system or apparatus such as known in the tradeas Prosperity 6A. It includes a dry cleaning washer 10 supported by feet11 and having an access door 12 through which apparel to be dry cleanedis inserted. It also includes a filter 13 supported by feet 14 andhaving a removable cover 15. The filter 13 is provided with an inletfitting 16 and an outlet fitting 17.

The dry cleaning solution is withdrawn from the Washer 10 through aconduit 20, a button trap 21 and a conduit 22 by means of a pump 23driven by an electrical motor, not shown. The pump discharges through aconduit 24 into the filter 13 through the fitting 16. The conduit 24 maybe provided with a sight glass 25. Thesolution is discharged from thefilter 13 through the discharge fitting 17, an upwardly extendingconduit 26, a horizontally extending conduit 27 and a downwardlyextending conduit 28 into the washer 10. Thus, the pump 23 operates tocirculate the solution from the washer 10 through the button trap 21,the filter 13 and back to the washer 10. A valve 29 and a sight glass 30may be located in the horizontal conduit 27 The conductivity device 31of this invention is preferably vertically arranged in the verticalconduit 26 adjacent the horizontal conduit 27 on the discharge side ofthe filter 13. In this connection the conductivity responsive device 31is connected by a reducing fitting 32 to the conduit26 and 'by aT-fitting 33 to the conduit 27. One through leg of the T-fitting 33 issecured to the conductivity responsive device 3-1 and the other throughleg thereof is closed by a plug 34. The normal leg is connected to thehorizontal conduit 27.

The details of construction of the electrical conductivity responsivedevice are illustrated in FIGURES 3 to 7.-

It is shown to be constructed for use with a two inch conduit system,that is, where the vertical conduit 26 is for-med from standard two inchpipe. Here, the electrical conductivity responsive device 31 includes acylindrical housing 36 which may be formed from a three inch pipe or itmay be [formed from a casting, if so I esired. The cylindrical housing36 is threaded at its lower end as indicated at 37 and is secured to thereducing coupling 32 which in turn is secured to the conduit 26. Thehousing is also threaded at its upper end as indicated at 33 so that itmaybe secured to the T-fitting 33 which in this instance is a three inchT-fitting wherein the through legs of the T-fitting are three inch andthe normal leg is of smaller size as, for example, a two inch leg forconnection to the horizontal conduit 27 when it is a two inch conduit.Concentrically located within the housing 36 are a pair of concentrictubular metallic electrodes 39 and 40. These electrodes 39 and 40 may bemade of any suitable metal which will not be afiected by the solution.For example,

the inner electrode 39 may be formed of No. 16 gauge seamless steeltubing having an outside diameter of 2% inch and the outer electrode 40may be formed of No. 16

gauge seamless steel tubing having an outside diameter of 2%. inch. Itwill be noted here that the inside diameter of the inner tubularelectrode 39 is substantially the same as the inside diameter of the twoinch conduit 26 so that the electrodes 39 and 40 will not restrict theflow of the solution through the dry cleaning system. The electrodes 39'and 40' are held in concentric relation the housing 36 by means of lowerand upper spacer members 41 and 42.

The lower and upper spacer members 41 and 42 are each provided with acentral opening 44 which corresponds to the inside diameter of the innerelectrode 39. The spacer members 41 and 42 are made of an electricalinsulating material such as Lucite. Adjacent the opening 44 in thespacer member there is provided an annular seat 45 which receives theend of the inner electrode 39. It is also provided with an annular seat46 of larger diameter for receiving the end of the outer electrode 40.Between the seats 45 and 46 the spacer member is provided with aplurality of openings 47 so that the solution in addition to flowingthrough the inner tubular electrode 39 is also allowed to flow betweenthe inner electrode 39 and the outer electrode 40. Substantially freeflow of the solution is provided between the electrodes 39 and 4-9because of the relatively large number of these openings 47. The innerelectrode 39 is secured to the lower spacer member 4-1 by means of ascrew 49 received in a counterbored hole 5th in the spacer member, thescrew 49 being screwed into a tapped hole in the lower end of the innerelectrode 39.

The lower spacer member 41 is secured in place in the housing 36 bymeans of a pair of screws 51 and 52 which are screwed into the spacermember 41. It is here noted that the screws 51 and 52 do not toucheither electrode 39 and 49 so that there can be no electrical conductionbetween the electrodes 39 and 40 and the housing 36 through these screws51 and 52. The screws 51 and 52 are sealed against leakage by washers orgaskets 53 which may be formed of Lucite. In this way the spacer member41 is secured to the housing 36 which in turn concentrically mounts thelower ends of the tubular electrodes 39 and 40. The upper spacer member42 is secured to the housing 36 by means of a pair of screws 54 and 58.The screw 54 is threaded into the upper end of the inner electrode 39 soas to make electrical contact therewith. The screw 54 is sealed againstleakage and is electrically insulated from the housing 36 by means of anelectrical insulator 55 which also may be made of Lucite. The screw 54has a tapped hole therein for receiving a screw 56 to form an electricalconnector for a conductor 57. The screw 58 is threaded into the upperend of the outer electrode 40 so as to make electrical contacttherewith. It is also sealed against leakage and electrically insulatedfrom the housing 36 by means of an insulator 55 and it is also providedwith a tapped hole for receiving a screw 56 for forming an electricalconnection to a conductor 59. Thus, the screws 54 and 58 in addition tosecuring the upper spacer member 42 and the upper ends of the electrodes39 and 40 in place, also act as electrical connectors for makingelectrical connection to the electrodes 39 and 49, respectively.

It is therefore seen that all of the solution being circulated throughthe dry cleaning system is circulated through the electricalconductivity responsive device 31, the solution passing through theinner electrode 39 and between the inner and outer electrodes 39 and 49.Thus, the electrodes 39 and 40 may operate continuously to measure ordetermine the electrical conductivity of the soluition." At the sametime the electrical conductivity responsive device 31' offerssubstantially no restriction or resistance to the flow of the solutiontherethrough. In this way accurate determinations may be made.

In FIGURES 8 to 11 the electrical conductivity responsive device 31 isconstructed for use with 'a three inch conduit system, that is, wherethe vertical conduit 26 is formed from a pipe of three inch diameter.Here, the housing 36 is made larger as, for example, from a four inchpipe and likewise the T-fitting 33 is a four inch fitting. However, theelectrodes 39 and 40 may be of the same size as in FIGURES 3 to 7 sothat they may be interchangeably used. Here, the spacer members aredesignated at 62 and 63. They correspond in all respects to the spacermembers 41 and 42 with the exception that they are provided with aplurality of outwardly extending ears 6 to form openings between thespacer members and the housing 36, these openings being designated at65. The ears 64 may be integrally formed on the spacer members 62 and 63or they may be made from separate pieces such as Lucite which in turnare secured to the spacer members 62 and 63 by a suitable cement such asethylene dichloride. The solution flowing through the electricalconductivity responsive device 31 in FIGURE 8 in addition to flowingthrough the inner electrode 39 and between the inner electrode 39 andthe outer electrode 49 also flows between the outer electrode 40 and thehousing 36. In this way substantially no restriction or resistance tothe flow of the solution is provided by the electrical conductivityresponsive device and yet, accurate measurements of the electricalconductivity of the solution may be obtained.

Referring now to FIGURES 1 and 2, the system uti lized in the practiceof this invention includes an electrical resistance responsive devicefor measuring or determining the electrical conductivity of the solutionflowing through the dry cleaning system. This electrical resistanceresponsive device may comprise an adjustable Wheatstone bridgearrangement. It has a terminal strip 71 and a selector switch 72cooperating with indicia 73 for determining the adjustment of thebridge. The bridge may be powered by any suitable source of electricalenergy transmitted thereto through line wires 74 and 75 connected toterminals 76 and 77, respectively. One of the legs of the bridge circuitmay be connected to terminals 78 and 79 which in turn are connected bythe conductors 57 and 59 to the electrodes 39 and 40 in the electricalconductivity responsive device 39.. In this way the electricalconductivity of the solution, as determined by the resistance to currentflow therethrough, is utilized for balancing and unbalancing the bridgein the electrical resistance responsive device 76), the balancing pointof which may be adjusted to any desired value by manipulating the knob72. The bridge circuit in the electrical resistance responsive device 70operates switching means for connecting the line wires 74- and 75 acrossthe terminals 80 and 81 and for connecting those line wires across theterminals 89 and 82. When the electrical conductivity of the solution isabove a predetermined value as determined by the setting of the controlknob 72, the line wires 74 and 75 are connected across the terminals 80and 81 by the switching mechanism. When the electrical conductivity ofthe solution is below the predetermined value, the line wires 74 and 75are connected across the terminals 80 and 82.

Water is supplied to the solution from a water reservoir 85 which issuitably supported in an elevated position as by securing the same tothe conduit 28 as indicated in FIGURE 1. Water is supplied to thereservoir 85 by means of a water supply pipe 86. A solenoid valveconsisting of a valve 87 and a solenoid operator 88 is located in thepipe 86 for turning on and ofi the water. The pipe 86 also has a secondvalve 89 which is controlled'by a float 9t) responsive to the level ofthe water in the reservoir 85. When the solenoid 88 is energized to openthe valve 87, water flows into the reservoir 85 up to a predeterminedlevel therein whereupon the float 9t) closes the valve 89 to shut offthe supply of water to the reservoir. Water is fed from the reservoir 85into the conduit 22 and, hence, into the circulating solution in the drycleaning system through a pipe 91 which is connected by a petcock 92into the conduit 22. By suitably adjusting the petcock 92 the rate ofwater feed into the water solution may be regulated. The pipe 91 ispreferably provided with a strainer 93 for keeping foreign matter out ofthe solution. The flow of water through the pipe 91 may be turned on andofr by a valve 94 operated by a solenoid 95. When the solenoid 95 isenergized, the valve 94 is opened to supply water to the solution andwhen the solenoid 95 is deenergized, the valve 94 is closed. A signallight 96 having an indicating lamp 97 is connected in parallel with thesolenoid 95 so that the signal light is illuminated while water is beingsupplied to the solution in the dry cleaning system. To prevent openingof the valve 94 when the 9 pump 23 is not running there is provided arelay having an operating coil 98 for operating a switch arm 99, theoperating coil 98 being connected by conductors 100 and 101 to thecontrolling switch for operating the motor which drives the pump 23.

In starting the dry cleaning system the water reservoir 85 is firstfilled with water and then the pump 23 is turned on for circulating thesolution through the washer and filter. The solution is checked for theamount of oil-soluble non-volatile dry cleaning detergent to assure thata proper amount ofthe detergent is present in the solution. Theautomatic control system is then activated. When the pump 23 is placedin operation, the switch 99 operated by the operating coil 98 is closed.If the electrical conductivity of the solution is below the desiredvalue as determined by the control knob 72, a circuit is completed fromthe line wire 74 through terminal 76, terminal 182, conductor 105,switch 99, signal light 97 and solenoid '95 connected in parallel,conductor 103, terminal 80 and terminal 77 back to the line wire 75.This energizes the solenoid 95 for opening the valve 94 to supply waterfrom the reservoir 85 to the conduit 22 and, hence, to the solution inthe dry cleaning system. The rate of application of the Water to thesolution is regulated by the petcock 92. At the same time the signallight 97 is illuminated. When the electrical conductivity of thesolution reaches the desired value, the aforementioned circuit is brokenand another circuit is completed from the line wire 74 through terminal7'6, terminal 81, conductor 104, solenoid 89, conductor 103, terminal 80and terminal 77 back to the line wire 75, this circuit being completedat the same time that the aforementioned circuit is broken. As a result,the signal light 96 is extinguished, the solenoid 95 is deenergized toclose the valve 94 to shut off the supply of water to the solution andthe solenoid 88 is energized to open the valve 87 to supply water to thereservoir 85 until the level of the Water in the reservoir reaches apredetermined value as controlled by the valve 89 in turn controlled bythe float 90. Thus, during the period that water is not being suppliedto the solution water is being supplied-to the reservoir 85 for fillingthe same. If for some reason the control apparatus should not operateproperly so as to tend to supply water to the solution in excessiveamounts, the amount of water so supplied is limited by the size of thereservoir 85'. In this way it is impossible to add excessively largeamounts of Water to the solution. Also in this way the correct amount ofwater is maintained inthe solution for providing maximum dry cleaning'efiiciency.

When garments are placed in the washer 10, they will absorb some of thewater in the solution and when this occurs, the control system of thisinvention automatically operates to replenish the water so absorbed soas to maintain at all times maximum cleaning efiiciency regardless ofthe character of the garments being cleaned and the moisture contentcarried by such garments. The signal light 96 is illuminated during thetime that water is being supplied to the solution and it is found thatunder normal operating conditions water will be supplied to the solutionduring the cleaning cycle for about two to five minutes, the cleaningcycle usually running from ten to twenty minutes depending upon the typeof garments being cleaned. If water is introduced intermittently duringa cleaning cycle for shorter periods, this means that the water is beingintroduced at too great a rate and to remedy this the petcock 92 isclosed oif somewhat in order to obtain the correct cycling. If water isadmitted to the solution for longer periods than this two to five minuteperiod, this indicates that something is wrong and the operator isadvised of this by the signal light 96. The amount of water introducedinto the solution may be regulated by adjusting the control knob 72 onthe electrical resistance responsive device 70, the knob being turned inone direction for increasing the amount of 10 water in solution and inthe other direction tor decreasing the amount of such Water.

While for purposes of illustration one main form of equipment throughthe utilization of which the method of this invention may be practicedhas been disclosed, other forms of equipment may become apparent tothose skilled in the art upon reference to this disclosure, andtherefore, this invention is to be limited only by the scope of theappended claims.

1 claim as my invention:

1. In the dry cleaning of fabrics by the two-bath method in a systemwhich includes a washer. adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer and filter and a pumpforcireulating through the Washer, filter and conduits awater-immiscible organic dry cleaning solvent which is activated bysmall proportions of an oil-soluble non-volatile dry cleaning detergentand Water so finely dispersed as to form a substantially clearhomogeneous solution, the steps which include placing the fabrics to bedry cleaned in the washer, circulating the said solution therethroughand continuously through said filter whereby to remove soil from saidfabrics and whereby, upon initial contact of said fabrics with saidsolution a portion of the Water in said solution is absorbed by saidfabrics, and, promptly upon said absorption occurring, automaticallyadmitting water into contact with said solution to effect at least asubstantial replenishment of said initially absorbed water, saidautomatic admission of water being effected in response to a change inthe electricalconductivity of said solution caused by said absorption ofWater from said fabrics by reason of the initial contact thereof by saidsolution, the electrical conductivity of said solution during theWashing cycle being maintained within the range of from about 10 to x10mhos.

2. In the dry cleaning of fabrics by the two-ba method in a system whichincludes a washer adapted to hold fabrics to be dry cleaned, a filter,conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a water-immiscibleorganic dry cleaning solvent which is activated by small proportions ofan oil-soluble non-volatile dry cleaning detergent and water so finelydispersed as to form a substantially clear homogeneous solution, thesteps which include continuously determining the electrical conductivityof the solution, placing the fabrics to be dry cleaned in the washer,circulating said solution therethrough and continuously through saidfilter whereby to remove soil from said fabrics and whereby, uponinitial contact of said fabrics with said solution, a portion of thewater in said solution is absorbed by said fabrics which decreases theelectrical conductivity of said solution, and, promptly upon saidabsorption occurring with resultant decrease in electrical conductivityof said solution, admitting water into contact with said solution inaccordance with the decrease in electrical conductivity of the solutionto effect at least a substantial replenishment of said initiallyabsorbed water, the electrical conductivity of said solution during theWashing cycle being maintained within the range of from about 10 to 12010- m-lros.

3. In the dry cleaning of fabrics by the two-bath method in a systemwhich includes a washer adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a Water-immiscibleorganic dry cleaning solvent which is activated by small proportions ofan oil-soluble non-volatile dry cleaning detergent and water so finelydispersed as to form'a substantially clear homogeneous solution, thesteps which include continuously determining the electrical conductivityof the solution, initially admitting, if necessary, water in contactwith said solution to bring the electricai conductivity and hence theWater content there'- of to desired values, placing a batchof thefabrics to be dry cleaned in the washer, circulating said solutiontherethrough and continuously through said filter for a desired intervalof time whereby to remove soil from said fabrics and whereby, at thebeginning of said time interval a portion of the water in said solutionis absorbed by said fabrics which decreases the electrical conductivityof said solution, and, during said time interval and promptly upon saidabsorption occurring with resultant decreases in electrical conductivityof said solution, admitting water into contact with said solution inaccordance with the decrease in electrical conductivity of the solutionto elfect at least a substantial replenishment of said initiallyabsorbed water, the electrical conductivity of said solution during thewashing cycle being maintained within the range of from about to 120 10mhos.

4. In the dry cleaning of fabrics by the two-bat method in a systemwhich includes a washer adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a waterimrniscibleorganic dry cleaning solvent which is activated by small proportions ofan oil-soluble non-volatile dry cleaning detergent and water so finelydispersed as to form a substantially clear homogeneous solution, thesteps which include continuously determining the electrical conductivity of the solution, initially admitting, if necessary, water incontact with said solution to bring the electrical conductivity todesired values, placing a batch of the fabrics to be dry cleaned in thewasher, circulating said solution therethrough and continuously throughsaid filter for a time interval of about ten minutes to twenty minuteswhereby to remove soil from said fabrics and whereby, at the beginningof said time interval a portion of the water in said solution isabsorbed by said fabrics which decreases the electnical conductivity ofsaid solution, and, for about two minutes to five minutes during saidtime interval and promptly upon said absorption occurring with resultantdecrease in electrical conductivity of said solution, admitting waterinto contact with said solution in accordance with the decrease inelectrical conductivity of the solution to etfect at least a substantialreplenishment of said initially absorbed water, the electricalconductivity of said solution during the washing cycle being maintainedwithin the range of from about 10 to 120x 10" mhos.

5. In the dry cleaning of fabrics by the two-bat method in a systemwhich includes a washer adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a dry cleaningsolution in the form of a water-immiscible organic dry cleaning solventwhich is activated by small proportions of an oil-soluble non-volatiledry cleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the steps which includeinitially adding said detergent and water to said dry cleaning solventand circulating said mixture through said washer and filter until saidsolution is formed, then placing the fabrics to be dry cleaned in thewasher, continuously circulating the said solution, during a washingcycle, through said washer and filter whereby to remove soil from saidfabrics and deposit the organic solvent-insoluble soil in said filterand whereby, upon initial contact of said fabrics with said solution aportion of the water in said solution is absorbed by said fabrics, and,promptly upon said absorption occurring, automatically admitting waterinto contact with said solution on the inlet side of said pump to elfectat least a substantial replenishment of said initially absorbed waterand to pass it through said filter before admission to said washer,

said automatic admission of water being effected by means of anelectrical resistance device responsive to a change "in the electricalconductivity of said solution caused 12. by said absorption of waterfrom said fabrics by reason of the initial contact thereof by saidsolution, the electrical conductivity of said solution during thewashing cycle being maintained within the range of from about 10 to 1O'mhos.

6. In the dry cleaning of fabrics by the two-bath method in a systemwhich includes a Washer adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer .and filter and a pump forcirculating through the washer, filter and conduits a dry cleaningsolution in the form of a water-immiscible organic dry cleaning solventwhich is activated by small proportions of an oil-soluble non-volatiledry cleaning detergent and water so finely dispersed as to form asubstantially clear homogeneous solution, the steps which includeinitially adding said detergent and water to said dry cleaning solventand circulating said mixture through said washer and filter until saidsolution is formed, then placing the fabrics to be dry cleaned in thewasher, continuously circulating the said solution during a washingcycle through said washer and filter whereby to remove soil from saidfabrics and deposit the organic solvent-insoluble soil in said filterand whereby, upon initial contact of said fabrics with said solution aportion of the water in said solution is absorbed by said fabrics, and,promptly upon said'absorption occurring, automatically admitting waterinto contact with said solution on the inlet side of said pump to clfectat least a substantial replenishment of said initially absorbed waterand to pass it through said filter before admission to said washer, saidautomatic admission .of water being effected in response to a change inthe electrical conductivity of said solution caused by said absorptionof water from said fabrics by reason of the initial contact thereof bysaid solution, all of said solution in the system, during any givenwashing cycle, being circulated past and in contact with the responseeffective means, the electrical conductivity of said solution during thewashing cycle being maintained within the range of from about 10 to120x10" mhos.

7. In the dry cleaning of fabrics by the two-bath method in a systemwhich includes a washer adapted to hold fabrics to bedry cleaned, afilter, conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a water-immiscibleorganic dry cleaning solvent which is activated by small proportions ofan oil-soluble non-volatile dry cleaning detergent and from about 0.2%to about 0.4%, by volume, of water so finely dispersed as to form asubstantially clear homogeneous solution, the steps which includecontinuously determining the electrical conductivity of the solution,initially admitting, if necessary, water in contact with said solutionto bring the electrical conductivity to within the range of from about10 to 120x lO' lmhos, placing a batch of the fabrics to be dry cleanedin the washer, circulating said solution therethrough and continuouslythrough said filter for a time interval of about ten minutes to twentyminutes whereby to remove soil from said fabrics and whereby, at thebeginning of said time interval, a portion of the water in said solutionis absorbed by said fabrics which decreases the electrical conductivityof said solution, and, for about two minutes to five minutes during saidtime interval and promptly upon said absorption occurring with resultantdecrease in electrical conductivity of said solution, admitting waterinto contact with said solution in accordance with the decrease inelectrical conductivity of the solution to effect replenishment of saidinitially absorbed water to an extent to bring it to within the range ofabout 01% to about 0.4%, by voltime.

8. In the dry cleaning of fabrics by the two-bath method in a systemwhich includes a washer adapted to hold fabrics to be dry cleaned, afilter, conduits interconnecting the washer and filter and a pump forcirculating through the washer, filter and conduits a dry cleaningsolution in the form of a water-immiscible organic dry cleaning solventwhich is activated bysmall proportions of an oil-soluble non-volatiledry cleaning detergent and from about 0.2% to about 0.4%, by volume, ofwater so finely dispersed as to form a substantially clear homogeneoussolution, the steps which include initially adding said detergent andwater to said dry cleaning solvent and circulating said mixture throughsaid washer and filter until said solution is formed, continuouslydetermining the electrical conductivity of the solution, initiallyadmitting, if necessary, water in contact with said solution to bringthe electrical conductivity to within the range of from about 40 to 10010- mhos, placing a batch of the fabrics to be dry cleaned in thewasher,

continuously circulatin said solution, durin a washin I cycle, throughsaid washer and filter for a time interval of about. ten minutes totwenty minutes whereby to remove soil from said fabrics and deposit theorganic sol-- vent-insoluble soil in said filter and whereby, at thebeginthe range of about 0.2% to about 0.4%, by volume, saidautomatically admitted water being introduced on the inlet side of saidpump whereby it passes, in said solution, through the filter beforepassage into the washer.

, 14 References Cited in the file of this patent UNITED STATES PATENTS1,810,660 Kritchevsky June 16, 1931 1,939,067 Legg Dec. 12, 19332,024,981 Reddish Dec. 17, 1935 2,150,031 Hatfield Mar. 7, 19392,276,681 ,Allison Mar. 17, 1942 2,349,992 ,Schrader May 30, 19442,440,386 Stein Apr. 27, 1948 2,475,023 Grimes July 5, 1949 2,599,583Robinson :et a1 June 10, 1952 2,614,026 Lascari Oct.14, 1952 2,621,673Hodgens Dec. 16, 1952 2,626,620 Smith Jan. 27, 1953 2,627,453 Sheen Feb.3, 1953 2,663,308 Hodgens Dec. 22, 1953 2,715,833 Fulton et a1 Aug. 23,1955 2,913,893 Mathews et a1 Nov. 24, 1959 FOREIGN PATENTS 388,897 GreatBritain Mar. 9, 1933 OTHER REFERENCES Senate Report No.--97, Report ofthe Committee on- The Judiciary, United States Senate, made by itsSubcommittee on Patents, Trademarks, and Copyrights, March 9, 1959, p. 8(Copy available at US. Govt. Printing Office, Washington, D.C.)

1. IN THE DRY CLEANING OF FABRICS BY THE "TWO-BATH" METHOD IN A SYSTEMWHICH INCLUDES A WASHER ADAPTED TO HOLD FABRICS TO BE DRY CLEANED, AFILTER, CONDUITS INTERCONNECTING THE WASHER AND FILTER AND A PUMP FORCIRCULATING THROUGH THE WASHER, FILTER AND CONDUITS A WATER-IMMISCIBLEORGANIC DRY CLEANING SOLVENT WHICH IS ACTIVATED BY SMALL PROPORTIONS OFAN OIL-SOLUBLE NON-VOLATILE DRY CLEANING DETERGENT AND WATER SO FINELYDISPERSED AS TO FORM A SUBSTANTIALLY CLEAR HOMOGENOUS "SOLUTION," THESTEPS WHICH INCLUDE PLACING THE FABRIC TO BE DRY CLEANED IN THE WASHER,CIRCULATING THE SAID "SOLUTION" THERETHROUGH AND CONTINUOUSLY THROUGHSAID FILTER WHEREBY TO REMOVE SOIL FROM SAID FABRICS AND WHEREBY, UPONINITIAL CONTACT OF SAID FABRICS WITH SAID "SOLUTION" A PORTION OF THEWATER IN SAID "SOLUTION" IS ABSORBED BY SAID FABRICS, AND, PROMPTLY UPONSAID ABSORPTION OCCURING, AUTOMATICALLY ADMITTING WATER INTO CONTACTWITH SAID "SOLUTION" TO EFFECT AT LEAST A SUBSTANTIAL REPLACEMENT OFSAID INITIALLY ABSORBED WATER, SAID AUTOMATIC ADMISSION OF WATER BEINGEFFECTED IN RESPONSE TO A CHANGE IN THE ELECTRICAL CONDUCTIVITY OF SAID"SOLUTION" CAUSED BY SAID ABSORPTION OF WATER FROM SAID FABRICS BYREASON OF THE INITIAL CONTACT THEREOF BY SAID "SOLUTION," THE ELECTRICALCONDUCTIVITY OF SAID "SOLUTION" DURING THE WASHING CYCLE BEINGMAINTAINED WITHIN THE RANGE OF FROM ABOUT 10 TO 120X10**-7 MHOS.